Apparatus, and associated method, for paging an access terminal in a radio communication system

ABSTRACT

An apparatus, and an associated methodology for a communication system in which an access terminal is paged by a page sent on a paging channel. Hashes are generated by a hash generator at an access network to identify where in the paging message that page indications are to be positioned. And, hashes are generated at the access terminal to identify where in a received page that page indications are located.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 11/970,921 filed on Jan. 8, 2008, which claims priority to theU.S. Provisional Application Ser. No. 60/884,369 filed on Jan. 10, 2007,the contents of which are incorporated herein by reference.

The present invention relates generally to a manner by which to page anaccess terminal of a radio communication system to alert the accessterminal of a pending call, or other communication. More particularly,the present invention relates to apparatus, and an associated method,that provides for the generation, sending, and analysis of a quick pagemessage upon a paging channel, such as a QPCH (quick paging channel)defined in an exemplary cellular communication system. The page messageis formed in a manner that reduces the likelihood of occurrence of falsewakeup of an access terminal. Excessive battery depletion, as a resultof false wakeup of the access terminal, is avoided.

BACKGROUND OF THE INVENTION

Advancements in communication technologies have permitted thedevelopment and deployment of new types of communication systems andcommunication services. Cellular telephony, and associated communicationservices available therethrough, are popularly utilized by many,typically providing users with communication mobility and also providingthe capability of communications when the use of wireline communicationsystems would not be practical or possible.

While early-generation, cellular communication systems providedprimarily for voice communications and only limited data communicationservices, newer-generation systems increasingly provide for high-speeddata communication services at variable data communication rates. ACDMA2000, cellular communication system that provides for EV-DO servicesis an exemplary type of new-generation, cellular communication systemthat provides for high-speed data services. Operational details andprotocols defining communications and operational requirements ofdevices of the system are set forth in an operating standardspecification. Various aspects of operation of the CDMA2000 EV-DOcommunication scheme remain to be standardized and certain parts of theexisting standard specification are considered for amendment. Varioussuccessor-generation communication schemes are also undergoingstandardization and yet others are envisioned to be standardized.

For instance, a revision to the standard specification, release B of theCDMA2000 EV-DO specification standard that defines a quick pagingchannel (QPCH) available upon which to broadcast access-terminal pagesby an access network (AN) to an access terminal (AT). The QPCH wasadopted in industry contributions 3GPP2 C20-20060323-013R1 and 3GPP2C20-20060323-003R1 and published in 3GPP2 document C.S0024-B V1.0.Generally, pages are broadcast by the access network to an accessterminal to alert the access terminal of a pending communication. And byso alerting the access terminal, the access terminal performs actions topermit the effectuation of the communication. Page indications broadcastupon the quick paging channel are broadcast in a manner that facilitatesreduced battery consumption of the access terminal. Increased batterylongevity is provided, reducing the rate at which a battery of theaccess terminal must be recharged. The access terminal is, as a result,able to be operated for a greater period of time between rechargings orbattery replacement. The aforementioned promulgations provide forbroadcast of a message including page indications upon a physicallogical layer that is monitored by the access terminal. The accessterminal monitors the QPCH prior to monitoring the control channel toreceive regular, control channel MAC (medium access control) messagessuch as page messages. A quick page message is broadcast upon the QPCHthat contains quick page indicators. The quick page message includes anumber of quick page indicator slots populated with quick pageindicators.

During operation, a mobile station hashes to a quick page indicatorlocation, i.e., slot, within the quick page message based upon a sessionseed, e.g., a 32-bit pseudorandom number. If the quick page indicator ofthe quick page indicator slot to which the access terminal hashesindicates that the access terminal is not being paged, the accessterminal enters into a sleep state, a reduced-power state, in which theaccess terminal does not remain powered at a level to receive theregular control channel MAC messages. Power savings is particularlysignificant in the event that the control channel MAC messages arelengthy and span multiple control channel frames or capsules.

In the existing scheme, however, the access terminal is susceptible tothe occurrence of a false wakeup, that is, the access terminal does notenter into a sleep state but, rather, the access terminal enters into anactive state to monitor the regular control channel for reception ofregular control channel MAC messages even though there shall be nomessage for the access terminal. Because the communication system is amulti-user system, there is a possibility that another access terminalthat is being paged has its page indication hashed to the same pageindication slot. As the number of access terminals that are paged in asystem increases, the likelihood of occurrence of a false wakeupcorrespondingly increases.

If a manner could be provided by which to reduce the occurrence of falsewakeups, improved battery longevity of the access terminal would bepossible.

It is in light of this background information related to paging by anaccess network of an access terminal that the significant improvementsof the present invention have evolved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a functional block diagram of a radio communicationsystem in which an embodiment of the present invention is operable.

FIG. 2 illustrates a graphical representation of the relationshipbetween the probability of occurrence of a false wakeup as a function ofthe number of pages in a multi-user communication system for variousnumbers of hashes.

FIG. 3 illustrates an exemplary quick page message generated pursuant tooperation of an exemplary embodiment of the present invention.

FIG. 4 illustrates an exemplary quick page message generated pursuant tooperation of another exemplary embodiment of the present invention.

FIG. 5 illustrates formation of an exemplary quick page message pursuantto operation of another exemplary embodiment of the present invention.

FIG. 6 illustrates a method flow diagram representative of the method ofoperation of an embodiment of the present invention.

FIG. 7 illustrates an example of the above procedure being used toselect paging indicators for an AT, AT1.

FIG. 8 illustrates another example of the above procedure being used toselect paging indicators for an AT, AT2.

DETAILED DESCRIPTION

The present invention, accordingly, advantageously provides apparatus,and an associated method, by which to page an access terminal of a radiocommunication system to alert the access terminal of a pending call, orother communication.

Through operation of an embodiment of the present invention, a manner isprovided to generate, send, and analyze a quick page message, such as aquick page message generated and sent upon a QPCH (Quick Paging Channel)defined in a CDMA2000 EV-DO cellular communication system.

The page message is formed in a manner such that, when analyzed, theaccess terminal is less susceptible to occurrence of a false wakeup. Byreducing the likelihood of occurrence of false wakeup, excessive batterydepletion that occurs as a result of false wakeup is less likely tooccur.

In one aspect of the present invention, hashing is performed at both anaccess network and at an access terminal using the same input number,such as a session seed defined in the CDMA2000 EV-DO operatingspecification standard or other pseudorandom number, or another inputnumber, such as an access terminal identifier (ATI). Hashing isperformed upon the input number in the same manner, independently, atthe access network and at the access terminal. Multiple hashes areformed by hashing the input number in different manners, e.g., such asby rotating the bit sequence of the input number to create differenthash values. Alternately, different hash functions are used to createthe different hashes. Formation of the multiple hashes is sometimesreferred to herein as multi-hashing. Each hash function operation iscarried out in the same manner at the access network and at the accessterminal so that the resultant hash values generated at the respectiveentities are identical. For instance, hashing is first performed at boththe access network and at the access terminal upon the input number innon-rotated form. Then, the hashing is performed, again at both theaccess network and at the access terminal, upon the input number whosebits are rotated by a first number of bits. If additional hashing isperformed, the access network and the access terminal both perform thehashing upon the input number, whose bits are further rotated, again inthe same manner at the access network and at the access terminal. Bitrotation also decorrelates the hashed values.

In a further aspect of the present invention, the hashing is performedupon the input number by operation of a hash function, or algorithm,upon the input number. The hash function, e.g., is time-varying orotherwise, in some manner, generates hash values that aretime-dependent. And, if desired, if multiple hash values are generated,the hash values are further caused to be dissimilar. That is to say,when multiple hash values are generated, a later-generated hash value iscaused to be of a value different than any earlier-generated hash value.

In another aspect of the present invention, the access networkidentifies the number of hashes and the number of page indications thatare to be included in a quick page message to page a particular accessterminal. A signaling message is generated that includes an indicationof the number of hashes or page indications that are going to bebroadcast by the access network to a particular access terminal within apaging message. The access terminal, from this signaling message,ascertains the number of page indications that are going to be directedto the access terminal in the quick page message. Responsive to thisreceived number, the access terminal performs hashing upon an inputnumber to form an appropriate number of hash values, and such hashvalues are used pursuant to analysis of the page message, when received,to identify where in the page message to detect values of pageindicators.

In another aspect of the present invention, the number of hashesperformed by the access network and, correspondingly, the number ofhashes performed at the access terminal, is a selectable number. Thenumber is selected, at least in part, based upon the number of pagesthat are to be made to other access terminals. And, more generally, thenumber of hashes is responsive to communication activity in thecommunication system. When many access terminals are paged, the numberof page indications, and hash values, per access terminal is, e.g., asmall value. And, conversely, when only a small number of accessterminals are to be paged, the number of page indications, and hashvalues, is, e.g., large. Generally, the number of hash values andresultant page indications per access terminal, populated into a pagemessage for a particular access terminal, is inversely proportional tothe communication activity, that is, the number of other pages that aremade to other access terminals during a particular period of operationof the communication system. Ideally, the number of page indications andhash values per access terminal is chosen in a way to minimize theprobability of false wakeup.

In another aspect of the present invention, the hash values determinewhere in the page message that the page indications are populated. Thehashing performed at the access network and at the access terminal arecarried out in the same manners. The page indication locations of a pagemessage in which the page indication values are populated are the samehash values that are generated at the access terminal, and the accessterminal detects and analyzes the corresponding page indicationlocations of the page message, once received at the access terminal.

In another aspect of the present invention, in the event that any of thevalues of the page indications populating the page indication locationscorresponding to the hash values indicate that the access terminal isnot being paged, the access terminal enters into a sleep state. Forinstance, if the access terminal detects any page indication value towhich the access terminal hashes and determines the access terminal isnot being paged, the access terminal enters into a sleep state. Thereby,the access terminal is more quickly able to enter into a power-saving,sleep mode. Conversely, if the access terminal identifies a pageindication value populating a page indication location that indicatesthat the access terminal is being paged and the access terminal knowsthat multiple page indications are broadcast to the access terminal inthe quick page message, the access terminal monitors for the same pageindication value in another page indication location to which the accessterminal hashes. If the first positive indication is a false indication,monitoring of a second, or other, page indication locations prior todetermining finally that the access terminal is being paged reduces thelikelihood of occurrence of false wakeup. Thereby, the access terminaldoes not enter into an active state to receive a communicationresponsive to a false wakeup indication. Improved power consumptioncharacteristics of the access terminal result, providing better batterylongevity.

In another aspect of the present invention, a hash generator, and anassociated hash generation mechanism or hash generation algorithm isprovided. The hash values generated by the hash generator ensure, orsignificantly reduce the possibility, that the hash values, used to hashto locations in a page message for paging of different access terminals,shall be the same value. The occurrence of hash-value “collision” isthereby reduced or eliminated.

In these and other aspects, therefore, apparatus, and an associatedmethodology, is provided for an access network that selectably generatesa first page message on a first paging channel. A page indicationpopulator is configured to populate the first page with a selectednumber of page indications. A hasher is configured to generate aselected number of hash values. Each hash value is determinative ofwhere the page indicator populates the first page message with a pageindication. The hash values selected by the hasher reduce, or eliminate,the possibility of multiple populations of the same location of the pagemessage with multiple hash values.

In these and other aspects, therefore, further apparatus, and anassociated methodology, is provided for an access terminal thatselectably receives a first page message on a first paging channel. Ahasher is configured to generate a selected number of hash values. And,a page indication detector is configured to detect values of pageindications populating the first page message. Hash values that aregenerated are used to identify to the page indication detector where inthe first page message to detect the values of the page indications.

Referring first, therefore, to FIG. 1, a radio communication system,shown generally at 10, provides for communications with accessterminals, of which the access terminal 12 is exemplary. Thecommunication system forms a multi-user communication system thattypically includes a large number of access terminals and a plurality ofconcurrent communication dialogs. While only a single access terminal isshown in FIG. 1, additional access terminals, analogous to the accessterminal 12, typically form a portion of the communication system.

Communications are effectuated between an access terminal 12 and a radionetwork 14, formed of fixed network infrastructure elements, such as abase transceiver station (BTS) 16 and a base station controller (BSC)18. The access network encompasses a geographical area within whichcommunications with the access network are possible. That is to say,when an access terminal 12 is positioned within the area encompassed bythe access network, the access terminal 12 is generally able tocommunicate with the access network, and the access network is typicallyable to communicate with the access terminal.

The communication system is operable in general conformity with theoperating protocols and parameters of an appropriate communicationspecification standard. The description set forth herein is exemplary,and the teachings of various embodiments of the present invention areimplementable in any of various types of communication systems.

As previously mentioned, the access terminal 12 is alerted, by broadcastof page messages when a communication, initiated at the network, is tobe terminated at the access terminal 12. A quick paging channel (QPCH),or analogous channel, is defined. Quick page indications, populating aquick page message, are of values that identify whether an accessterminal 12 is being paged. However, also as noted previously,particularly during times of heavy usage, a false wakeup of the accessterminal might occur due to a quick page indication in the messageintended for one access terminal is broadcast within a slot that is alsoused by another of the access terminals. False wakeup prevents an accessterminal from entering into a power-saving sleep mode.

Accordingly, pursuant to an embodiment of the present invention, theaccess network includes apparatus 24, and the access terminal includesapparatus 26, that operate to reduce the likelihood of the occurrence offalse wakeup. The elements of the apparatus 24 and the apparatus 26 arefunctionally represented, implementable in any desired manner,including, for instance, by algorithms executable by processingcircuitry.

The elements forming the apparatus 24 are implemented at any appropriatelocation of the access network 14, including, as illustrated, at the BTS16 and BSC 18 or distributed amongst such entities as well as others.

Here, the apparatus 24 includes a quantity of hashes/page indicationsper access terminal determiner 32. The determiner 32 is coupled toreceive, as input indicia, indications of network activity on the lines34 and 35. The network activity is quantified, for instance, in a numberof page values. The network is aware, e.g., of the number of accessterminals that shall be paged. Or, the number of page values comprises,e.g., an expected number of pages, an average number of prior pages, orother paging quantity indicia. Responsive to the indication of thenetwork activity, the determiner 32 determines the number of hashes thatare to be generated and the number of page indications that are to beprovided pursuant to paging of an access terminal in a quick pagingmessage. In an alternate implementation, the number of hash values is aset number, e.g., a fixed number greater than one. The fixed number oftwo, e.g., appears to work well when the number of page indicationlocations in a quick page message is about one hundred eighty. Thenumber of hash values and number of page indications correspond. Anindication of the determined quantity 44 is provided to a signalingmessage generator 36 and to a hash generator, a “hasher”, 38.

A number known to both the access network and to the access terminal,such as a session seed or other pseudorandom number, or a number such asan access terminal identifier (ATI) is provided to the hash generator38, here represented by way of the line 42. The hash generator 38 hashesthe number. That is to say, a hash function is performed upon the numberto generate a hash value. Different hash values are provided by, e.g.,rotating the number provided to the hash generator 38 and performing thehash function, or algorithm, thereon. Multiple hash values aregenerated, for instance, by operating upon multiple rotations of thenumber. With an ideal hash function, all values are equally likely to begenerated. An exemplary hash function comprises a mathematical “modulo”operation. A time factor, known to both the access network and theaccess terminal, such as a system clock time, is, in one embodiment,further provided to, and used by, the hash generator 38 in the formationof hash values. Such factor is represented by line 43 in FIG. 1.

In a further embodiment of the present invention, the hash functionforms a hash mechanism that reduce, or eliminate, the possibility thatthe same hash value shall be selected as a result of multiple hashings.That is to say, in the further embodiment, unique numbers are generated,reducing the amount of “collisions” with, or of, access terminals thatare not being paged.

For example, the hash function comprises a so-called Algorithm S(selection sampling technique) taken from Kruth's “The Art of ComputerProgramming”, 3d Edition, Chapter 3.4.2.

In another implementation, a generate Unique List PI Bits_A algorithm isused in which:

-   MBA=maximum number of bits available to be set-   nPI=number of PI bit locations to select-   iPI=number of PI bit locations found so far-   jPI=index running through iPI selections-   rnd=new random bit to be set. If this is the (jPI+1)st location we    need to add jPI to it, since jPI locations are already taken-   uListPI[1 . . . nPI]=sorted list of unique indexes of nPI bits to    select within MBA;

The algorithm is, e.g., comprises of this pseudo code:

generateUniqueListPIBits_A( MBA, nPI ) returning uListPI[ ] {  Verifyarguments and make sure enough bits are available to be set;  Select arandom across all bits and assign it to the first item in the list, e.g. uListPI[1] = random(1, MBA);  Now one by one select random bits fromremaining bits, e.g.  foreach ( iPI = 1→ nPI−1)  {   Let rnd = random(1,MBA − iPI), since iPI bits are not available   Insert the new rndlocation (from among available bits) to uListPI, e.g.   foreach ( jPI =iPI→ 1)   {    Shift indexes in uListPI to insert rnd, so uListPIremains sorted e.g.    if ((rnd + jPI) > uListPI [jPI]) found locationso break from loop;    else uListPI [ jPI + 1] = uListPI[ jPI ];   }  uListPI [ jPI + 1 ] = rnd + jPI; Note jPI=0 if the loop exited without  break  }  Return uListPI[ ]; }

In another implementation, a generate Simple Almost Unique List PI BitsD algorithm is used in which:

MBA=maximum number of bits available to be set

nPI=number of PI bit locations to select

iPI=number of PI bit locations found so far

jPI=index running through iPI selections

rnd=new random bit to be set.

auListPI[1 . . . nPI]=list of almost unique indexes of nPI bits toselect within MBA;

The algorithm is, e.g., comprised of this pseudo code:

generateSimpleAlmostUniqueListPIBits_D( MBA, nPI ) returning auListPI[ ]{  Verify arguments and make sure enough bits are available to be set; Select a random across all bits and assign it to the first item in thelist, e.g.  auListPI [1] = random(1, MBA);  Now one by one select randombits from remaining bits, e.g.  foreach ( iPI =1→ nPI −1)  {   Let rnd =random(1, MBA − iPI), since iPI bits are not available   Increment rndby 1 for each smaller index found so far, e.g.   foreach ( jPI = iPI →iPI)   {    if ((rnd) > auListPI [jPI]) rnd++;   }   auListPI [ iPI +1 ]= rnd;  }  Return auListPI[ ]; }

In another implementation, a generate Simple Almost Unique List PI BitsK algorithm is used in which:

MBA=maximum number of bits available to be set

nPI=number of PI bit locations to select

jPI=index running through iPI selections

rnd=new random bit to be set.

auListPI[1 . . . nPI]=list of almost unique indexes of nPI bits toselect within MBA;

vBitsSet[1 . . . MBA]=boolean local vector representing bits set so far

The algorithm is, e.g., comprised of the pseudo code:

generateSimpleAlmostUniqueListPIBits_K(MBA, nPI ) returning auListPI[ ]{  Verify arguments and make sure enough bits are available to be set; Set vBitsSet[ ] vector to false;  Now one by one select random bitschecking for single collisions, e.g.  foreach ( jPI = 1→ nPI)  {  Select a new random number, e.g.   Let rnd = random(1, MBA);   Do asimple single rehash in case of collision, e.g.   if (vBitsSet[rnd]) rnd= ((rnd+MBA/nPI) mod MBA);   vBitsSet[rnd] = TRUE;   auListPI[jPI] =rnd;  } Return auListPI[ ];

The random number generation mentioned in the above, exemplary pseudocodes uses, e.g., existing methods with different keys and/or DECORRvalues.

The signaling message generator 36 to which the value determined by thedeterminer 32 is provided generates a signaling message, here generatedupon the line 45, that identifies the quantity determined by thedeterminer. The signaling message 45 is broadcast to the access terminal12, thereby to alert the access terminal of the determined quantity. Thesignaling message generator 36 may operate in conjunction with the QPCHgenerator 54 and include the quantity in the QPCH message. The hashvalues created by the hash generator 38 are provided to a pageindication populator 48. The page indication populator 48 is alsoprovided with a network communication request, here provided by way ofthe line 52. The page indication populator 48 selects page indicationvalues depending upon whether the access terminal is to be paged. Forinstance, when an access terminal is to be paged, the page indicationvalues are logical “1” values. In one implementation, all values areinitially logical “0” values and then set as appropriate. The pageindication values and their associated page indication locations,defined by the hash values generated by the hash generator 38, areprovided to a QPCH, or other, message generator 54. The messagegenerator 54 forms a page message 56 that includes a plurality of pageindication locations. The page indication populator 48 populatesselected page indication locations of the message with the pageindication values. The locations populated with a page indication valueare determined by the hash values generated by the hash generator 38. Inlike manner, page indications are formed for other access terminals andhash values are generated to define at where in the page message thepage indications intended for other access terminals are populated inthe message generated by the message generator 54. When the resultantmessage is broadcast by the access network, access terminals, such asthe access terminal 12, are provided with an indication of whether theaccess terminal is to be paged.

Transceiver elements of the base transceiver station 16 cause broadcastof the messages generated by the message generator 54 of the apparatus24 upon a radio air interface, represented in FIG. 1 by the arrow 62.The message is delivered to the access terminal 12 as well as otheraccess terminals within reception range of the broadcast message. Theaccess terminal 12 includes transceiver circuitry, here represented by areceive part 64 and a transmit part 66. The receive part 64 operates toreceive signals sent thereto, such as the messages generated by theapparatus 24 of the access network. And, certain of the detected signalsare provided to the apparatus 26. Of significance here are detections ofthe signaling message generated by the signaling message generator ofthe access network and of the page message generated by the messagegenerator 54.

Indications are provided to a signaling message detector and analyzer68. The detector and analyzer 68 operate to detect the contents of thesignaling message and analyze the detected message to ascertain thenumber of hashes, or page indications, per access terminal indicated inthe message. Indications are provided, here by way of the line 72, to ahash generator 74. The hash generator 74 is also provided with values ofthe input number, here indicated to be provided by way of the line 76,known to both the access network and access terminal. The time factor,known to both the access network and access terminal is also provided tothe generator 74, here represented by way of line 77. The hash generator74 operates in manners analogous to operation of the hash generator 38of the access network to perform hash functions upon the input number.And, the input number provided to the hash generator 74 corresponds tothe input number provided to the hash generator 38 on the line 42. Thenumber of hash values generated by the hash generator 74 corresponds tothe number identified by the detector and analyzer 68. Hash valuescreated by the hash generator 74 are provided to a QPCH (Quick PagingChannel), or other, page message detector 82. The hash values created bythe hash generator 74 identify to the page message detector 82 which ofthe page indication locations that should be monitored to determinewhether a page is broadcast to the access terminal. The messagebroadcast by the access network and detected and operated upon by theaccess terminal is an atomic message. That is to say, all of the bitsare received in a single message. Responsive to detections made by thedetector 82, an indication is provided to an access terminal (AT) statecontroller 84 to control the state into which the access terminal isplaced. And, when the QPCH message indicates that the access terminal ispaged, the access terminal begins to monitor a second page channel, forbroadcast of a second page message thereon. The receive part of theaccess terminal also monitors the second page channel. The pageindications in the message generated by the message generator 54 aretherefore sent pursuant to, i.e., in furtherance of the sending of thesecond page message on the second page channel.

In the event that the first quick page indication slot monitored by themessage detector 82 indicates no page message broadcast to the accessterminal 12, the state controller 84 places the access terminal 12 intoa sleep mode. If a first of the quick page indication slots monitored bythe detector 82 indicates a page to have been broadcast, but a second ofthe quick page indication slots monitored by the detector 82 indicatesno page, the state controller 84 also causes the access terminal 12 toenter into a low-power, sleep mode. Additional page indications, if morethan two, are analogously monitored. The occurrence of a false wakeup isreduced as one or more additional quick page indications are monitoredto provide further indication of whether a page has been sent to theaccess terminal.

FIG. 2 illustrates a graphical representation, shown generally at 102,that shows the relationship between the occurrence of false wakeup andthe number of pages in the communication system 10 shown in FIG. 1,pursuant to exemplary operation. Plots 104 illustrate the generalproportional relationship between the number of pages to accessterminals in a multi-user communication scheme and the occurrence offalse wakeup, represented in terms of probability. Four plots, plots104-1, 104-2, 104-3, and 104-4, are shown. The plot 104-1 isrepresentative of the relationship when a single page indication isprovided to a particular access terminal in a page message to alert theaccess terminal of the page. A single hash value is generated, and thepage indication is populated in a single page indication locationdetermined by the single hash value. The plot 104-2 is representative oftwo page indication bits provided in the page message to alert aparticular access terminal of the page. Two hash values are generated,and the page indication locations in which the page indications arepositioned are determined by the two hash values. The plot 104-3 isrepresentative of use of three page indications in a page message toalert a particular access terminal of the page. Three hash values aregenerated and their values are determinative of the positioning of thethree page indication locations in which the page indications arepopulated. And, the plot 104-4 is representative of the relationshipbetween false wakeup occurrences when four page indications are used ina page message to page the access terminal.

Review of the plots shows that the number of page indications in a pagemessage that provides the lowest false wakeup probability for a givennumber of pages in the communication system, i.e., network activity,varies with the number of pages. Pursuant to operation of an embodimentof the present invention, advantage is taken of this relationship in theselection of the number of page indications to use per access terminal.Such selection is made, e.g., by the determiner 32 shown in FIG. 1.Selection is made in such a way as to minimize the false wakeupprobability. For each number of pages, i.e., network activity, selectionis made of the number of page indications that are to be used to page,in the quick page message, an access terminal. Using, for instance,plots analogous to the plots 104 shown in FIG. 2, the lowest curve foreach of the number of pages, i.e., network activity, is selected.Analysis indicates that, when a number of pages is relatively small, thelowest probability of false wakeup occurs when greater number of pageindications per access terminal are utilized. Conversely, at highernumbers of pages, i.e., network activity, lesser numbers of pageindications provides the lowest false wakeup probabilities. Changeoveroccurs at various thresholds, indicated in the representation of FIG. 2when plots cross one another.

Once determination and selection is made at the access network,indication of the selection is provided to an access terminal. Thenumber of page indications, known at both the access network and at theaccess terminal, permits operation of the apparatus 24 and 26 incoordinated manner. In the exemplary implementation, the page indicationvalues populating a quick page message are all received in the samemessage. The access terminal need not wake up at different times forseparate bits as all of the bits of the message are received at once inthe same message. Furthermore, the same page indicator values are hashedinstead of, as previously utilized, making divisions into multiplephysical groups. And, the page indication locations defined by the hashvalues are further able to be generated in a manner such that the pageindication locations are dissimilar. Rotation of the input number usedin the generation of the hash values decorrelates the hash values, andthe introduction of time variance in the hash function also provides forhash value dissimilarity.

FIG. 3 illustrates an exemplary quick page message, shown generally at108. The message is generated, for instance, with respect to theconfiguration shown in FIG. 1, at the message generator 54. The quickpage message includes a plurality, here 33, page indication locations112, numbered as 1-33. Initially, each page indication location is setto logical “0” values. Page indications for four access terminals 12,identified as AT1, AT2, AT3, and AT4, are represented in the message108. A hash generator generates hash values of 8 and 6 for the accessterminal AT1. And, page indication locations 8 and 6 are populated withvalues to indicate whether the access terminal AT1 is paged. Here, thelogical values “1” are inserted into the page indication locations 8 and6 that identify that the AT1 is paged. Analogously, with respect to theaccess terminal AT2, the hash generator generates hash values of 7 and21, and page indications are inserted into page indication locations 7and 21 to identify that the access terminal AT2 is paged. Hash values 21and 13 generated with respect to the access terminal AT3 cause pageindication locations 21 and 13 to be populated with page indication bitsto identify, here, that the access terminal AT3 is paged. And, hashvalues generated with respect to the access terminal AT4 of 25 and 3cause the page indication locations 25 and 3 to be populated with pageindication bits, here again to identify that the access terminal AT4 ispaged. In this implementation, any of the page indication locations ofthe message 108 are available to be populated with page indication bitsassociated with any of the access terminals. And, as indicated at thepage indication location 21, a page indication location might include apage indication bit associated with more than one of the accessterminals. Ideally, the hash generator generates hash values that permiteven, viz. equal, distribution of page indication values across theentire message 108. Each hash for a particular access terminal hashesover the same page indication location in contrast to conventionalprocedures. And, through use of the time factor, the occurrence ofrepeated generation of hash values of similar values, and correspondingpopulation of the same page indication locations, for a particularaccess terminal, is unlikely.

FIG. 4 illustrates another message, here shown generally at 116 thatalso includes thirty-three page indication locations 112 that arepopulated with page indication values, here again to page accessterminals AT1, AT2, AT3, and AT4. Here, the message is divided into twogroups, a first group 118, and a second group 122. Initially, here also,each page indication location is set to logical “0” values. In thisimplementation, only a single page indication location per group isavailable for page indicator values associated with a particular accessterminal. That is to say, with respect to the access terminal AT1, asingle page indication location in the first group is available, and asingle page indication location in the second group is available. When ahash value generated by the hash value generator is of a value withinthe first group, another hash value must be of a value within the secondgroup. Ideally, the hash generator generates hash values that permiteven distribution of page indication values across each group of themessage. And, as shown in the representation of FIG. 4, a pageindication location is available to each of the access terminals in thefirst group and in the second group. The example shown in FIG. 4 is foran implementation in which two page indication bits are available withinthe page message per access terminal. If additional page indication bitsare available, the page message is divided into additional numbers ofgroups of substantially equal size, and the page indication locationsare correspondingly made available in each of the additional numbers ofgroups.

FIG. 5 illustrates a quick page message 126 and the manner by which ahash generator operates pursuant to another embodiment. Here, four pageindication locations are made available to the access terminal AT1 overthe thirty-three bits of the quick page message. And, again, each pageindication location is initially set to logical “0” values. When a hashvalue is selected and the page indication location 112 determinedtherefrom is used, that page indication location is no longer availableto that access terminal at which to populate the message with anotherpage indication value. That is to say, a hash value cannot be repeatedfor that access terminal. In the representation shown in FIG. 5, a firstpage indication value is populated in page indication location 10. Herealso, ideally, the hash generator generates hash values that permit evendistribution of page indications across all of the available pageindication locations. As noted below, when a page indication location isused, the location becomes no longer available. Page indication location10 is no longer available for the access terminal AT1. A next-generatedhash value is of 11 and a page indication bit is inserted into the pageindication location 11. Thereafter, neither page indication locations 10nor 11 are available. A subsequently-generated hash value of 20 causesthe page indication value to be inserted into page indication location20. And, thereafter, page indication locations 10, 11, and 20 are nolonger available. A fourth-generated hash value of 5 is generated, andthe page indication location 5 is populated with a page indicationvalue. In this implementation, use of a time factor is generally notrequired.

FIG. 6 shows a method flow diagram, shown generally at 132,representative of exemplary operation of an embodiment of the presentinvention for a communication system that selectably generates pagemessages on a first channel.

First, and as indicated by block 114, a signaling message is generatedthat indicates a selected number of hashes to page indications thatshall be generated within a page message sent upon the first channel.Then, and as indicated by the block 116, a page message is formed of thepage indications corresponding to the selected number of hashes.

As indicated by the block 118, the signaling message is sent upon thefirst channel. The signaling message is detected, indicated by the block122, at an access terminal together with the selected number of hashesto quick page indicator slots that are contained in the signalingmessage. And, as indicated by the block 124, the page message isdetected at the access terminal, and a determination is made whether thepage message includes the page indications corresponding to the selectednumber of hashes.

The aforementioned embodiments describe different ways that multiplebits per page can be hashed in a Quick Page message. In these methods, anumber of bits from n available bits are hashed for each AT.

The hashing method that provides the lowest false wakeup probability fora number of bits hashed per page is as follows:

Hash a first bit of the available n bits at random as the first pagingindicator.

Hash a second bit of n−1 bits at random, excluding the first hashed bit,as the second paging indicator.

Hash a third bit of n−2 bits at random, excluding the first and secondhashed bits, as the third paging indicator.

. . . and so on depending upon the number of hashed bits per page.

The following describes details of ways of implementing this hashingmethod that are very simple and efficient to implement in an AT and inan AN. For example, the following pseudocode illustrates an improved wayof implementing this hashing method:

  // Init For( i = 0; i < maxBits; i++)  Bits [ i ] = i; For( j = 0; j <maxPI; j++) {  Rnd = random( 0, maxBits − j − 1);  PI [ j ] = Bits[ Rnd];  Bits +[ Rnd ] = Bits [ maxBits − j − 1];} Return PI [ ];

The method uses an array, Bits, with a number of entries correspondingto the number of available paging indicators. The array is initializedsuch that each entry is equal to its index. For the first pagingindicator a first number is hashed randomly based upon the number ofpaging indicators. This number is used as an index into the array, Bits;the value of the array at this index is selected as the first pagingindicator. The value of the array at this index is then assigned to thevalue of the last entry in the array. For the second paging indicator asecond number is hashed randomly based upon the number of pagingindicators minus one. This number is used as an index into the array,Bits; the value of the array at this index is selected as the secondpaging indicator. The value of the array at this index is then assignedto the value of the entry in the array next to the last entry in thearray. The method continues based upon the number of paging indicatorsper page.

This method can be integrated with the Quick Page message published inthe 3GPP2 specification C.S0024-B v1.0, using the hash function insection 14.4 of C.S0024-B v1.0.

FIG. 7 shows an example of the above procedure being used to selectpaging indicators for an AT, AT1. It should be noted that although theabove pseudocode uses 0 as the index to the first array entry, FIG. 7uses 1 as the index to the first array entry. 151, 152, 153, 154, and155 illustrate an array and show how the entries are arranged aftersuccessive steps. Entries in array 151 are shown below the indexes intothe array; each value in the array is shown below the correspondingindex. The array has the same number of entries as the number of pagingindicators available for hashing on the QPCH; in this example there are33 available paging indicators, so there are 33 entries in the array. Inthis example, there are four paging indicators per page, so four pagingindicators will be selected. The array is first initialized such thateach array entry is equal to its associated index; this is shown by 151.Next a first value in the range 1 to 33 is randomly hashed; in thisexample the hashed value is 6. The array entry at index 6 (in this case,6) is chosen as the first paging indicator and is shown shaded in array151. The array value (6) at the index value of the first hash is thenswapped with the array value at the last entry in the array (33).

The updated array after this swap step is shown by 152. Next a value inthe range 1 to 32 is randomly hashed; in this example the hashed valueis 29. The array entry at index 29 (in this case, 29) is chosen as thesecond paging indicator and is shown shaded in array 152. The arrayvalue (29) at the index value of the second hash is then swapped withthe array value at the next to last entry in the array (32).

The updated array after this swap step is shown by 153. Next a value inthe range 1 to 31 is randomly hashed; in this example the hashed valueis 4. The array entry at index 4 (in this case, 4) is chosen as thethird paging indicator and is shown shaded in array 153. The array value(4) at the index value of the third hash is then swapped with the arrayvalue at the second to last entry in the array (31).

The updated array after this swap step is shown by 154. Next a value inthe range 1 to 30 is randomly hashed; in this example the hashed valueis 8. The array entry at index 8 (in this case, 8) is chosen as thefourth paging indicator and is shown shaded in array 154. The arrayvalue (8) at the index value of the fourth hash is then swapped with thearray value at the third to last entry in the array (30). The updatedarray after this swap step is shown by 155. After this step, four pagingindicators have been selected and are shown as the final four entries inthe array.

160 shows the content of a quick page message with the paging indicatorsfor only AT1 set. Paging indicators 4, 6, 8, and 29 are equal to ‘1’ andall other paging indicators are equal to ‘0’.

It should be noted that in the particular example of FIG. 7, there is noeffect on the result of swapping array entries. The hashed valuesthemselves are the same as the paging indicators. In other instances,the same value may be hashed more than once; in such a case the selectedpaging indicator will be different from the hashed value and this willbe shown in FIG. 8.

FIG. 8 shows another example of the above procedure being used to selectpaging indicators for an AT, AT2. It should be noted that although theabove pseudocode uses 0 as the index to the first array entry, FIG. 8uses 1 as the index to the first array entry. 201, 202, 203, 204, and205 illustrate an array and show how the entries are arranged aftersuccessive steps. Entries in array 201 are shown below the indexes intothe array; each value in the array is shown below the correspondingindex. The array has the same number of entries as the number of pagingindicators available for hashing on the QPCH; in this example there are33 available paging indicators, so there are 33 entries in the array. Inthis example, there are four paging indicators per page, so four pagingindicators will be selected. The array is first initialized such thateach array entry is equal to its associated index; this is shown by 201.Next a first value in the range 1 to 33 is randomly hashed; in thisexample the hashed value is 11. The array entry at index 11 (in thiscase, 11) is chosen as the first paging indicator and is shown shaded inarray 201. The array value (11) at the index value of the first hash isthen swapped with the array value at the last entry in the array (33).

The updated array after this swap step is shown by 202. Next a value inthe range 1 to 32 is randomly hashed; in this example the hashed valueis 23. The array entry at index 23 (in this case, 23) is chosen as thesecond paging indicator and is shown shaded in array 202. The arrayvalue (23) at the index value of the second hash is then swapped withthe array value at the next to last entry in the array (32).

The updated array after this swap step is shown by 203. Next a value inthe range 1 to 31 is randomly hashed; in this example the hashed valueis 11. The array entry at index 11 (in this case, 33) is chosen as thethird paging indicator and is shown shaded in array 203. The array value(33) at the index value of the third hash is then swapped with the arrayvalue at the second to last entry in the array (31).

The updated array after this swap step is shown by 204. Next a value inthe range 1 to 30 is randomly hashed; in this example the hashed valueis 30. The array entry at index 30 (in this case, 30) is chosen as thefourth paging indicator and is shown shaded in array 204. The arrayvalue (30) at the index value of the fourth hash is then swapped withthe array value at the third to last entry in the array (30). Theupdated array after this swap step is shown by 205; it should be notedthat the values shown in 205 are the same as the values shown by 204 arethe same because the fourth hash happened to be the same as the third tolast index into the array (30). After this step, four paging indicatorshave been selected and are shown as the final four entries in the array.

210 shows the content of a quick page message with the paging indicatorsfor both AT1 from FIG. 7 and AT2 from FIG. 8 set. Paging indicators 11,23, 30, and 33 associated with AT2 are equal to ‘1’; paging indicators4, 6, 8, and 29 associated with AT1 are equal to ‘1’ and all otherpaging indicators are equal to ‘0’.

There is another method that can be used to obtain equivalent results aswith the above method, but without using an array; this alternativemethod is suitable for low numbers of paging indicators

For example, suppose there are 33 bits available for paging indicatorsand there are two paging indicators per page. A first hash will hash anumber randomly from 1 to 33. A second hash will hash a number randomlyfrom 1 to 32. If the result of the first hash is not equal to the resultof the second hash, the paging indicators will be equal to the result ofthe first hash and the result of the second hash. If the result of thefirst hash is equal to the result of the second hash, then one pagingindicator will be 33 and the other paging indicator will be equal to theresult of the two hashes. For example, suppose 9 is chosen for the firsthash and 14 is chosen for the second hash; in this case, the pagingindicators would be 9 and 14. As another example, suppose 8 is chosenfor the first hash and 8 is chosen for the second hash; in this case,the paging indicators would be 8 and 33.

As another example, suppose there are 33 bits available for pagingindicators and there are three paging indicators per page. A first hashwill hash a number randomly from 1 to 33. A second hash will hash anumber randomly from 1 to 32. A third hash will hash a number randomlyfrom 1 to 31. If the results of all of the three hashes are alldifferent, then the paging indicators will be equal to the result of thefirst, second, and third hashes. If the results of all three hashes arethe same, one paging indicator will be 33, another paging indicator willbe 32, and the other paging indicator will be the hashed value. If theresults of the first and second hashes are the same, but different fromthe third hash, then one paging indicator will be 33, another will bethe value of the first and second hashes, and another will be the valueof the third hash. If the results of the first and third hashes are thesame, but different from the second hash, the one paging indicator willbe 33, another will be the value of the first and third hashes, andanother will be the value of the second hash. If the results of thesecond and third hashes are the same, but different from the first hash,the one paging indicator will be 32, another will be the value of thefirst hash, and another will be the value of the second and thirdhashes. For example, suppose 10 is chosen for the first hash, 19 ischosen for the second hash, and 3 is chosen for the third hash; in thiscase, the paging indicators would be 10, 19, and 3. As another example,suppose 12 is chosen for the first hash, 12 is chosen for the secondhash, and 12 is chosen for the third hash; in this case, the pagingindicators would be 12, 32, and 33. As another example, suppose 7 ischosen for the first hash, 7 is chosen for the second hash, and 21 ischosen for the third hash; in this case, the paging indicators would be7, 21, and 33. As another example, suppose 25 is chosen for the firsthash, 1 is chosen for the second hash, and 25 is chosen for the thirdhash; in this case, the paging indicators would be 1, 25, and 33. Asanother example, suppose 19 is chosen for the first hash, 8 is chosenfor the second hash, and 8 is chosen for the third hash; in this case,the paging indicators would be 8, 19, and 32.

This alternative method can similarly be used for four and more pagingindicators per page, but the logic will be increasingly complex becausethe number of combinations of duplicate hashes increases for largernumbers of paging indicators per page.

Thereby, through operation of an embodiment of the present invention, anaccess terminal is able better, and quickly, to determine whether a pageis broadcast thereto. If a quick page message, page indication locationto which the access terminal hashes fails to include an indication thatthe access terminal is being paged, the access terminal enters into areduced power state. The occurrence of false wakeup is less likely tooccur due to the multi-hashing to the multiple quick paging indicationslots.

1. A method in an access terminal, the method comprising: monitoring aphysical air interface channel for a message broadcast by an accessnetwork; detecting for a first indicator at a first page indicationlocation in the message, the first page indication location based upon afirst hash value that is generated at the access terminal using a samemanner that the access network uses to populate the message with thefirst indicator; detecting for a second indicator at a second pageindication location in the message, the second page indication locationbased upon a predetermined location known to both the access terminaland the access network; and causing the access terminal to enter achanged state if both the first indicator and second indicator aredetected.
 2. The method of claim 1 wherein the detecting for a firstindicator further comprises generating a first hash value from a numberknown to both the access network and the access terminal.
 3. The methodof claim 2 wherein the detecting for a first indicator further comprisessequentially modifying the number known to both the access network andthe access terminal in a known way to generate a plurality of hashvalues.
 4. The method of claim 3 wherein sequentially modifying thenumber known to both the access network and the access terminal furthercomprises sequencing by a time factor known to both the access networkand the access terminal.
 5. The method of claim 1 wherein the first pageindication location and the second page indication location comprise twonumbers of a set of N page indication locations.
 6. The method of claim5 wherein the detecting for a first indicator further comprises hashinga number from 1 to N−1 to determine the first page indication locationand the detecting for a second indicator identifying the second pageindication location as location N.
 7. The method of claim 1 wherein thepredetermined location is different than the first page indicationlocation.
 8. The method of claim 1 wherein the causing the accessterminal to enter a changed state further comprises commencing thedetection for a page message.